Apparatus for generating and receiving electromagnetic waves.



R. A. FESSENDEN. APPARATUS FOR GENERATING AND RECEIVING ELECTROMAGNETIC WAVES.

' APPLICATION FILED AUG,Z6. I904. 1,158,123.

2 SHEETS-SHEET I.

H I NIIIIIIITI /4 p j /0 li f'bzas s: [Itllr Patented Oct. 26, 1915.

R. A. FESSE NDEN.

APPARATUS FOR GENERATING AND RECEIVING ELECTROMAGNETIC WAVES.

APPLICATION FILED AUGJG, I904.

Patented Oct. 26, 1915.

2 SHEETS-SHEET 2- UNITED STATES PATENT OFFIQE.

REGINALD A. FESSENDEN, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR,,BY ,MESNE ASSIGNMENTS, TO SAMUEL KINTNER, 0F PITTSBURGH, PENNSYLVANIA, AN'D HALSEY M. BARRETT, OF BLQOMFIELD, NEW JERSEY, RECEIVERS.

APPARATUS FOR GENERATING AND RECEIVING ELECTROMAGNETIC WAVES.

Patented Oct. 26. 1915; Application fi led August 26, 1904 Serial No. 222,293.

1 158 123 Specification of Letters Patent.

f0 all whom it may concern:

Be it known that I, REGINALD A. F ESSEN- DEN, a citizen of the-United States, and a resident of Washington, District of Golumbia, have invented certain new and useful Apparatus for Generating and Receiving Electromagnetic Waves, of which the following is a specification.

The invention herein described relates to improved apparatus for generating andreceiving electromagnetic waves.

It relates more especially to improvements in methods of wireless telegraphy by electromagnetic waves.

1n the accompanying drawings forming a part of this specification Figures 1, 2,3 and 4 are diagrammatic views illustrating my invention, Fig. 2 is a partial detail section of a coil support, Fig. 5 illustrates a method of using one form of this invention, Fig.6 illustrates a modification of the arrangement shown in Fig. 1 and Fig. 7 is a modi fication of the device in Fig. 4.

In Fig. 1, 1 is an aerial grounded at 7 and having an inductance 9 in the circuit of the aerial to ground. 2 and 6 are preferably equal inductances and 3 and, 5 capacities, also preferably equal and all also in circuit of the aerial to ground. 4 is a spark gap and 8 a source of current such for example as a transformer. On the discharge being made to pass across the spark gap 4 oscillations are caused in the circuits 2, 3, 4 and 4, 5 and 6. These cause oscillations in the sending conductor consisting of the vertical '1, and its connection toground. The circuits 2, 3 and 4 and 4, 5 and 6 are preferably tuned so as to have the same period or fre quency as the sending conductor as a whole, taken fromthe top of the aerial to the ground 7. Instead of attaching aerial 1 and inductance 9 at the junction of 2 and 3, the aerial may be inductively connected by using the coil 6 as primary transformer and the coil 19 as the secondary, as shown in Fig. 6.

Fig. .2 shows a means for varying the oscillation frequency of the device shown in Fig. 1. Here 1 is the aerial, 7 is the ground and 2, 6 and 9 are inductance coils, 11 is an insulating grooved roller, 10 is an insulating grooved wheel, 12 and 13 are grooved rollers preferably conducting, 15 is an insulating shaft and 14 is a handle, 9 is a brush adapt- .ed to follow the spiral groove in 9, 10. The

diameter of the roller and the shape of the wheel 10 are so adjusted empirically that on turning the handle 14 and varying the inductances 2 and 6 the inductance 9 is caused to vary in such a way that the circuits 4, 2, 3 and 4, 5, 6, and the circuit from the top of the sending conductor to ground are all changed at thesame rate, so that all remain in tune with one another.

There are a number of advantages in the use of the system shown in Fig. 1, among others the advantage that this arrangement acts so as to give twice the voltage on the aerial that (on account of the difference in phase between points a and b) is generated by the source 8. Another advantage is that the discharge gap is not in series with the aerial, and hence produces no distortion or diminut i0 n.- A third is the fact that the system is an absolutely symmetrically constructed one and hence lends itself to very sharp tuning. Where the sending conductor is inductively connected as at 19 of Fig. 6 the sending con- .ductor is of course tuned to the same fre quency as the local circuits 4, 2, 3 and 4, 5, 6.. Fig. 3 shows an alternative form of construction in which 1 is the aerial grounded at 7 through the condensers 3' and 5 preferably equal and through the inductances 2 an-d 6 also preferably equal and the spark gap 16. 18 is a source of voltage and 17 is an impedance. Here the circuits 2, 3, 16, and 5, 6, 16 and the tuned sending conductor from the top of the aerial to ground are all resonant to the same frequency. 16 is a multiple spark gap consisting preferably of a number of metallic cylinders of good heat conductivity and arranged so as not to become so much heated under the action of thedischarge as to alter. its character during sendmg.

Fig. 4 shows the apparatus of Fig. 1 used to efi'ect a double increase in voltage. Here 1 is the sending conductor; 2, 6, 20 and 23 are inductances, 3, 5, 21 and 22 are capacities, 24 is the discharge gap, and 7 1s a ground. Upon a source of current being applied to the spark gap 24 and a discharge caused to pass, a potential of approximately four times that of the potential of the source is caused to operate upon the vertical 1, the phase difference causing twice the voltage difference at c and d that there is at a and Z) the latter being twice that at 24. Here as before the local circuits and the sending conductor (as a whole) are resonant to the same frequency.

Fig. 5 shows similar apparatus applied to the receiving end. Here 31 is an aerial grounded at 7. 32 and 30 are preferably equal inductances. 25 and 29 are capacities also preferably equal. In the location corresponding to that of the spark gap in Fig. 1, is the primary 26 of a transformer the secondary 27 of which acts to affect the receiver 28. The circuit including the receiver 28 and the secondary 27 is preferably tuned by any method well known in the art to the frequency of the received oscillations, as are also the circuits 32, 26, 25 and 26, 29, 30

which form circuits from the top of the aerial to the ground 7. The number of turns and windings and the inductance of corresponding coils 80, 32 may be equal and for some purposes are preferably equal, but they may be either larger or smaller while still utilizing the method herein described and claimed.

By the term symmetrical resonating system as used herein is meant a system comprising an antenna or radiating portion and one or more circuits connected thereto for prolonging the oscillations, said antenna and circuits being so arranged and constructed that the curve representing the intensity of the received or emitted radiation is symmetrical on both sides of the point of maximum radiation, said point being a single and not a double point. In other words the curve of intensity of radiation and wave length has a single hump instead of the double hump or camel back shape.

I claim herein as my invention:

1. Wireless telegraph apparatus comprising the combination with a tuned radiating circuit, of another tuned oscillating circuit with an adjustable tuning element arranged to equally and sin'mltaneously vary the period of both said circuits.

2. In wireless telegraph apparatus, the combination with an open or antenna circuit, and an associated closed oscillating circuit with the same periodicity, of a tuning element common to the open and closed circuits, and ar anged to simultaneously and equally vary the periodicity of both circuits by moving one tuning element.

3. Apparatus for wireless telegraphy comprising a radiating antenna circuit, means to prolong and render uniform the wave trains radiated thereby, including a multiple spark gap and several condensers shunting parts of said spark gap.

-l. lVireless telegraph apparatus comp-rising a radiating antenna circuit, a local circuit adapted to prolong the radiation including a multiple spark gap, and a separate condenser circuit shunting a part of said gap, substantially as described.

5. The combination with several adjustable oscillation circuits. of a tuning device connecting the several circuits and having an adjustable tuning element a'rranged to equally and simultaneously varythe electrical periods of the several circuits, substantially as described.

6. The combination with several interdependent resonant circuits of a tuning device having an element common to said circuits and adjusted so that the variation of said REGINALD A. FESSENDEN.

Witnesses:

Tiioa'ras 1. BROWN, LEONA FLATHERS. 

